SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6518762b53589ba0e5379b6b1c3096cffaf8978839d3cfe14e3be76951bd352c' 
  AND token = 'aq6w2Y5/cUB4XuenuUmjAUDacPZpaDVJaCf1tLquJr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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