SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '151e436ed952b275b27829e7d3dc1fac86d9aa88b3a8f66aa1f23bd94fcddd3f' 
  AND token = 't6XYJhm5aGXJM3woK+rvEdhD+UGkzLZQYCybcrd2FUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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