SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71dde2e0782e3e6335344479bbec3e9bc8af011e2265a1717e229180878c75d0' 
  AND token = '1HEpeyaEEFnibb/nehH+oThcWqmYv+YTElZMv8vJOlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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