SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4bd575460ac0953690e36234904cc6500a5517e5f94fab863a0bd82e512ec15' 
  AND token = 'aQJwsjpjXZn7NdAzvB5wL+0cQCZIDO8vShSupXszKWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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