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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e70d5202809d50b5eddba912ee6601a5d5589e93907e8ab88b9d3ecfcbfd8a2c' 
  AND token = 'DSlfmKtx1I0RmsDiGjZ3WhzWWYblLIq/Z+cf4/xWjl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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