SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7e4bbb1efe9fae854d3ed6a9424ed0b729c7467cb33401787e4dea1de42da05' 
  AND token = 'ZnYEO0UOso9djqq1iVolazft2NOyNu+DErKfN0gCxX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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