SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9b9346b3fe4a81013a7a52eaf49eb09a37b409b1d65c28aab83deaa737d818a' 
  AND token = 'Z+JtXuQGinZjFokEYFOJjmPM/bwBOqOnmBuSHz6hqss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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