SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a491e4369c5af5ff0f5423a209713f68e34cd9fcf11581fa708fe29be7710859' 
  AND token = 'cl94p5VxD4IKHSDAhdqNLVXXpXciQDGg+VM/ZrQlWCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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