SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f83f40f288fa508e55fc325f011a4c62d2e159bb95c0de50807ed709c60ad517' 
  AND token = 'KiSOJBRPVTm2hH0Zg5UuIhCz96hmm8KtrjmHvAg+Qh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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