SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73d321150c5940ae296603618bb328281466f6ff2bfe266b97da803571aa03c0' 
  AND token = 'jgepgAO31zIO5J/gFOVxYK0essHWujB8ZywXQrjVOo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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