SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '5ab26355dd2926fbe0f6f8bef2efc8ab00440da5be91c38ed773d7a6f98791a3' 
  AND token = 'LO51+sqIODYhjyqoneMLYV0ilHh1smsxPyrHAZIHT0k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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