SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '7e7ce8a0539e0710a9644fac171a11ee314255b4e5d0d0168381887d51396da9' 
  AND token = 'YarKdjPWw3SQpCSowV9GqAmFzyNr7a2d9NW2exgjDO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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