SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cda2e37235f97670b0743e195a4bf966fd8f78a156c2372dbf8b8991bcfdb15' 
  AND token = 'vUAImUWUwitJnzvOdjGd1Qpbvc7/BTCPEPC/8InStmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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