SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74d6c554d9ddd5a1ef240ab62c855dd4f46e3c4170d55b83b0ae2cdefca523c4' 
  AND token = 'xCZm6XdDj2NuWaONvdrH+RwS2GlymxthL5qmsmxPrOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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