SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db2b65b2409057bf640950b2a1bc8b65420775cf79a48a44ee7daa401ac32120' 
  AND token = 'MQO4k07gcLKWYTbryeouYFTpEskpWORfyXeoFiiMxGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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