SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4c998dd953dada71952d7b1c36147c4d9b21dd8dc67412fe9086b7320034841' 
  AND token = 'kSXxyC3rInDDk986yHrt3c/NJneEHk+4ERCBReieoPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}