SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eac0730fc12cbdbdb0c8aeb65365f2dd6ca1f9408bc3293783da2861be5c8ff' 
  AND token = 'hDBqwR6CXLnOya+BBnCFCH7QVPQnbyKmT/yXotUdJOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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