SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fe8042f9d52703250f71145fd5d798359eca2d2a83545ce047838f5dddf906a' 
  AND token = '84k5Y5LJ35ZbHjmtYXmDfFWQc2WIOvnOJXDVqG4df1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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