SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8f7c11453d0a27068349e19a645dad824755dd416624aa5d07e6c168c89faca' 
  AND token = '1fg1Ci5OFvTBaKcWRhjMyqVSekgVDFF7pLi7Fledkvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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