SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba37ee99196f539e9dd1cee39180ac2f6731c6b88e24a2bfc5882f78ba1f90d3' 
  AND token = 'TqgXVBAFRBKIxmnt/hgBXvJ6TbQ/bOZUCRQHcaUtkNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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