SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40841d272c0021ffbd1f61249ac052777fed495173276830a32300f2250fb2c9' 
  AND token = 'bTw+HTJsr7NtLwGCRl645pvTEGttyagNpuZ/Ga3AkiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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