SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9738d750bf52e72f6c19090385db97f3bfc744e15b084b15127761cf92ccf06' 
  AND token = 'SJJfI+2ulUWdz9q+JWbQKULUaH2urgZ1eoxRpEM1Dx8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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