SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '503ccab0ac371a4f6988a3383ebd2cfa7d73be16dfabdf79cf75749a39dedefc' 
  AND token = 'fju5MAeuDvR2Er9DDiuCbox3ql9vosJfXhX5mhsdz14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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