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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd87036c84d9183e7fb6e17132a366725e3184686e76c4d7d30a57c8dfbd515b5' 
  AND token = 'BvZdtjYpsTbg7ZXCE07QzKew3QeH3Iwtj6itdg2rIrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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