SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6d044472c39114d9aa39d5ceaae44744dcf0242db9c084c1a03309360a73462' 
  AND token = 'yeiU5s8ukvoibRkUTtRPQVO4RbofEeJ9qii07eJNpxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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