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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ab506ee8fc28532dbdbfa2a23e898be96b80361888605ad17c2e6d04ba4ad645' 
  AND token = 'c4OdIgLcrT3OSfj9u2UUgoF1/oazbuCktDbL4BUPQ6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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