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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cb6bf0bce1821ab6d8c22cdeb569771ead4ce76a8c089d65320b83f227081e75' 
  AND token = 'YrUdGT7UItvjlljrE85Jv/msUXo87boK2npgUZqo18Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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