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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cefe96b75a95ed7190bbb1fe016e6ac3c1360884654af9dadc65890ad9f1c6a' 
  AND token = 'MBVvGgh0wR7pGfHw3hjcZ4fZCwaqZKSVu1Ho3QKTQD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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