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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b99758f8a1f8ac1353075bd96847e2a6f1717b3fad7e0c19ef61b3b331d73e3a' 
  AND token = 'PyzpVmSmdzL+hzetYlHEY+QYHw7wxGT8yMbSMeZ8S/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}