SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c2251133679ea4b0299337ec2b175270de87f332a49dd3ecd215649ba78c265' 
  AND token = 'TPoI5uHkNb2ki0ZAeDoZmitoILKDD7SzAGmOPkPiDqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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