SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c922ed51ec69af7597388ed5300ff0e1e65bd897d36549dbb0012ee4a15484b8' 
  AND token = 'l8vp3XosEP66stf44vY5zcJvK9fIArh/7JQbZztmQ1I=' 
  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"
    }
  }
}