SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e268323263fcf7ec1658f14da26c7b73f1aafe620eebd501848b167ae8564f84' 
  AND token = 'yNaIghi1KXsvnMtjtmn3mkdffDflJm1JD1nHC+9/++s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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