SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b481687f0cd6a09802fafc956670c39ecf7198662786d47dcef16ca881d8a80e' 
  AND token = 'x7v6qbcU93lVD5o31NhU+NpRaIjKGnVL/73nVJgX9Gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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