SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9a234beddc518d4ef178794a825626fd28143be636ace338db64bf01a8f6583' 
  AND token = '7MCqnQOtwwXkdar/NZpVUvFeyrp0M3T7iyxDFBn9ANc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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