SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12f00d356baf113d2f34abf3e95e058e95ecdbbf88689b74b4122b48aa30bbde' 
  AND token = 'QjSAviycr6RdQrV87qjLsJ4pANrDZr7ffThLAxyJZgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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