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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71e51fbe8bd0859bdaf5ec3bcd2bf34e4a47b08969d11ae1f69e9d37dd7028cd' 
  AND token = 'FCfaaTt1v9AGA64YFQSy7CnUPT2AJmTTSocDqQqJ7ps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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