SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d6cfbdc8c1d6ef5d7d1e326acf0821395ccf4f7327578108e890546a375ed6b' 
  AND token = '1SnZNk1wgz2Hh0X+hfZ++Et1MQNwbCYHmBwJK7ZNCAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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