SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a79aba7096e40f8f2cd4e4795309e5782bdf7aac9c85468bc60bb47204fdb974' 
  AND token = 'lK3Elw+aYShlZ1XC99H5AAZKSLjIVXeuVRKCqdAP+Jo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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