SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6910a393b930e418ee667511c5c1513edf6d6de73128af22141416a5e409357b' 
  AND token = 'OTBQbzfbGU+jG+lOh+J03fYwR9X4UmUfPA6Jmv0b3CY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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