SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55ea203e16746d0ff1f4aba1d0ce13e751ed67bacd35613c090881af1c09f454' 
  AND token = 'wsXjMkP7d32FPEEH4mWqygdB9itMEUMANy6d7gC/QlE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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