SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e69950341ed7ce1b2f5f444c6e30b75be376fc07e0b153e963216def6d3f3887' 
  AND token = 'v/0hAHZvcdhECkHSvQwsS8hUjTwKtKSQY0/N0zMUgFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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