SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3d39cd74ec0b01566430282bab1297eef0cc60cf215557446666acd7f5ad7df' 
  AND token = 'yWpcSYEGEA1YatIS5dgbx6oxtwK+fswCKd+BvmcWdQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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