SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffc7653a62190c75f98f38019b6bb949356066eea25d2d6faac0038587c95faa' 
  AND token = 'CLqhi3Wv+zXiaN+ubFOsqs190q+Cq+jyT/AGCCwZakw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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