SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'e0f744207f20cccbc40277a3207d41953e19a0762af9cc8176a5898c10c51350' 
  AND token = 'ag8FWLR6Cgwccu2iwrBmKHzIeegCVa18CoUAssnwvHo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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