SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30a3072038e961d2da068609f294983d125cd31d079b8bf1f21903a5d598828c' 
  AND token = 'o5gTHvEeAVP+qJus9YvHTP0bFj+RMQBwK2ZniMVoppA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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