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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c6e123d190ea87cdf07abee49c5c8948e1d0b7cd6af5a990e5fcfb3ef82c5757' 
  AND token = 'ZWEcEXAphhfjX4omQo9ZvMZM8fg2Dr+EaDoFtdIqQrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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