SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75a2cd67f080b83fca0593b6feab78e38ac48463a9ff628706e8dfb85cadc3e3' 
  AND token = 'K1ANWtG9+CWZBxoxjgJVMVjPzljvnOelDFAuzcDMVro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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