SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bab044ff11a336beed4038b17057304da8edc327fc84907c577d2e3da978f19' 
  AND token = 'vHM36+938ThmYp7QAz5KzAMJ0Cm1jdoXx2FikxgbZuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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