SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ed18ae225b789fad553f1994c869d557192b6698160f1956f9bee996be58518' 
  AND token = 'yRAtFCjbeSnaE19YicJnuyucYPKQuL7+WlEAJ4ZIQbg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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