SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '388bc4e0c7024227475ce286be00e58a9fb5f07eb3350e122b6a12cacd752caa' 
  AND token = 'mjLmp38cltsKBn0NR3PBO9DDNG70w5IHLZXvJ1Yq+2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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