SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ef268cd2aba8915a8a5e02ab2b6b168d90d9e421f6a8d0d235920047681800' 
  AND token = 'kkOIESwV7gbpcUXzx4knRuMrYVvPwyAKwXnruw0J/RI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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