SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88d334a4f9d2482aa36845b3325afdb6764d8e5aefeb18aa9a60d1fcb1362bdb' 
  AND token = '+fi0u245nRavGs7ZctamrDDOzxCI9o6+NIDMStOe3UQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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