SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2f394179d4030d5582b1b6c1ebd0908fb5d879a3857adf70d6379942dc35d8a' 
  AND token = 'HatP/gp0vEzy6sdcHmrp+a3JLcN4ujGOzr47Rw3XZVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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