SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '300deb19d17ba48dec9551dbfb08b80453a7e54753134ebefc2aa17fc69954e6' 
  AND token = 'ppzDtRlTz4+oRgcoHDw//QYuIIiFD8NPYni946FJT94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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