SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ffb0574eaf397f48b782528f2f587f3d6fa488b88a46844bf9f688cbcff218d' 
  AND token = 'p7PfuCNLJwYiFSoFKQYXA+l3/WGhDbsitz9V6PVmh20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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