SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2291e1b841990c48640d58acf4ac5714f99f68b2236299a390c1bb4068bfef3' 
  AND token = 'l409+0LLUoY6wZCzTLBkTDbOZZ9Z5Z35YVvE+zq79dE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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