SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75932d7ee7a76bacf701ea7d99d1f9fea05b4f019e16d69db0b69148e9907bd7' 
  AND token = 'vwjHFcjQiS0Pjf41Uec/qt47Gpg0Z1z5PeWvI4G2nes=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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