SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da2da6bcb9b105ca855b8554ff65986c043f494952e3bbce9e62db092c2e2578' 
  AND token = 'NVytvE9uIJdetUL8/uNeMhJu22zWCsd39tZPponHonc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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