SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87bad0f331d3be9cad441aeba2c721c4604946ea109fe511435d1b0cae8d9c78' 
  AND token = 'mmBGcVqoraz1MpQurXPzpkO6GSDsWYhAMqY5waxkEyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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