SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a801f19272bb048a7d314ed35ade353fbe0e0685b9593f6294a838661cb2b75e' 
  AND token = 'V/EVMyDvbIoyy4nLQWkGNUxcY47XKSg2NKh4FDYdgqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}